There are electronic cameras that generate image data at an image-capturing element having color filters that represent a plurality of colors and are provided at predetermined positions and implement image processing such as noise removal, edge emphasis and color conversion on the image data.
In such an electronic camera, the color components assigned to the individual color filters (e.g., CMYG: cyan, magenta, yellow and green, or RGB: red, green and blue) at the image-capturing element determine the calorimetric system used on the image data input side. However, the calorimetric system of the image data generated at the image-capturing element undergoes calorimetric system conversion processing to be converted to the YCrCb calorimetric system constituted of a brightness (or luminance) component Y and color components Cr and Cb which better suits the characteristics of the human visual system, so as to achieve better efficiency in the image processing including the noise removal and the edge emphasis and to enable standardized image compression such as JPEG.
This calorimetric system conversion processing may be realized by generating a Y component a Cr component and a Cb component for each of the pixels constituting the image data.
For instance, when generating these components directly from the image data generated at the image-capturing element, the Y component is generated by adding the color information at pixels present in the vicinity of a “processing object pixel (pixel to be processed)” undergoing the calorimetric system conversion processing and the Cr component and the Cb component for the processing object pixel are generated based upon differences among the color information at nearby pixels in an electronic camera in the related art.
However, since a plurality of sets of color information corresponding to the pixels present within a predetermined range which contains the processing object pixel are simply added together to generate the Y component, the color information at these pixels becomes averaged to result in a loss of the high-frequency component in the image data obtained at the image-capturing element in the electronic camera. Consequently, the image in the YCrCb calorimetric system obtained through the calorimetric system conversion processing becomes blurred.
It is to be noted that there are electronic cameras provided with an image-capturing element having R, G and B color filters arrayed in a Bayer array, which implement interpolation processing in order to obtain color information corresponding to all the color components, i.e., R, G and B, for each pixel and generate the Y component, the Cr component and the Cb component by using the color information obtained through the interpolation processing. However, since the interpolation processing is implemented for all the color components in the calorimetric system at the image-capturing element without fail during the calorimetric system conversion process, the efficiency of these electronic cameras is poor.